Alkaline Peptone Water : Principle, Composition and Cultural …

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Clinical materials containing a small number of Vibrio should be inoculated into an enrichment medium before plating onto a selective medium, such as TCBS Agar. Alkaline Peptone Water is an excellent enrichment broth for Vibrio species.

The American Public Health Association recommends this medium for enrichment of Vibrio species from seafood, infectious materials, and other clinical specimens such as feces.

 Principle of Alkaline Peptone Water

  • The medium’s relatively high pH (approximately 8.4) provides a favorable environment for the growth of Vibrio species.
  • Amino acids and other nitrogenous substances are provided by the peptic digestion of animal tissue.
  • Sodium chloride maintains osmotic balance.
  • Turbidity in tubes indicates growth when compared to an un-inoculated tube (control).
  • Enrichment broth growth is used for plating on selective media. A pure culture is recommended for biochemical identification.

Composition of Alkaline Peptone Water

IngredientsGms / Litre
Peptic digest of animal tissue10.000
Sodium chloride10.000
Final pH ( at 25°C)8.4±0.2

Type of specimen

  • Seafood
  • Infectious materials
  • Other clinical specimens such as feces.

Preparation procedure

Label the ready to use bottle. Inoculate the sample and Incubate at specified temperature and time.

Quality Control

AppearanceSterile clear Alkaline Peptone Water in bottles.
Color and Clarity of prepared mediumLight yellow colored clear solution
Reaction8.20- 8.60
Cultural ResponseCultural characteristics observed after incubation at 35-37°C for 18-24 hours.
Alkaline peptone water
Alkaline peptone water

Cultural Response on Alkaline Peptone Water

Vibrio cholerae ATCC 15748luxuriant
Vibrio parahaemolyticus ATCC 17802luxuriant

Storage and Shelf Life

Store between 2-8°C. Use before expiry date on the label.


  1. Gilligan, Janda, Karmali and Miller, 1992, Cumitech 12A, Laboratory Diagnosis of Bacterial Diarrhea, Coord. Ed.
  2. Forbes B. A., Sahm A. S., and Weissfeld D. F., Bailey & Scotts Diagnostic Microbiology, 10th Ed., 1998, Mosby
  3. Isenberg, (Ed.), 1992, Clinical Microbiology Procedures Handbook, Vol. I, American Society for Microbiology. Washington, D.C.

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About the Author: Labweeks

KEUMENI DEFFE Arthur luciano is a medical laboratory technologist, community health advocate and currently a master student in tropical medicine and infectious disease.

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